This invention pertains to a zipper for a reclosable package, such as a bag manufactured by a form, fill and seal apparatus, wherein the base of at least one of the zipper strips has apertures that allow packaged product, such as powder, to pass through the apertures and return to the interior volume of the reclosable package.
In the prior art, it is known to use a zipper with a female profile and a male profile in the manufacture of a reclosable package, such as a bag manufactured by a form, fill and seal apparatus. However, it is further known that if the reclosable package is filled with a fine powder product, then the fine powder or particulate matter can enter the female profile and degrade the performance of the zipper by blocking insertion of the male profile. Furthermore, if the user cleans this fine powder product from the female profile, this powder tends to be discarded rather than returned to the reclosable package. Moreover, such cleaning of the female profile can tend to contaminate any fine powder product that is returned to the reclosable package.
U.S. Pat. No. 6,299,353, entitled “Zipper for Reclosable Container with Apertures Passing Through Female Profile” and assigned to the assignee of the instant application, discloses a zipper with a female profile wherein spaced apertures are formed in the base thereof. The apertures communicate with the powder-containing interior volume of a reclosable package. When fine powder product becomes lodged within the female profile, an arrow-shaped male element of the male profile can push the lodged fine powder product through the apertures in the base of the female profile, to return the powder to the interior volume of the reclosable package. Since the legs of the female profile, as well as the male element of the male profile, remain intact, there is no degradation of the sealing provided by the zipper. Moreover, the direction of travel of the fine powder product through the apertures is substantially the same as the travel direction of the male element as it enters the female profile. As the fine powder product can be returned to the interior volume of the reclosable package without directly contacting the consumer, the fine powder product tends to be returned to the interior volume of the reclosable package free of contamination. To prevent powder from entering the female profile through the apertures, the female profile material that is cut to form the apertures may be left attached along an edge, thereby forming a flap that can serve as a simple one-way valve to permit powder to be removed from the female profile via the apertures, while preventing powder from entering the female profile via the apertures.
Flexible plastic zippers in which the male profile does not have an arrow shape are well known. For example, in one type of flexible zipper, the female profile comprises a pair of spaced legs or hooks having inwardly pointing detents, while the male profile comprises a pair of spaced legs or hooks having outwardly pointing detents, When the male profile penetrates the female profile, both legs of the male profile are located in the space between the legs of the female profile, with the detents of the male and female profiles being latched or interlocked to hold the zipper closed. For zippers of this type that are incorporated in packaging containing powder or other particulate matter, the male profile as well as the female profile can become clogged with powder or particles. Therefore, it would be highly desirable to redesign such zippers to be powder-resistant, i.e., the zipper should be designed to prevent the male profile, as well as the female profile, from becoming clogged with powder or other particulate matter.